[tex]i^7 + \dfrac 1{i^4}\\\\=i^2 \cdot i^2 \cdot i^2 \cdot i + \dfrac 1{i^2 \cdot i^2}\\\\=(-1)(-1)(-1)i + \dfrac 1{(-1)(-1)} ~~~;[ i^2 = -1] \\\\\ = (-1)^3 i+ \dfrac 1{(-1)^2} \\\\=-i+1[/tex]
